package game

import (
	"errors"
	"strconv"
	"strings"
)

// errNotPrimed marks the first PDH sample after opening a query: rate-based
// counters (like engine utilization) need two collections before they
// return meaningful values.
var errNotPrimed = errors.New("GPU engine counter needs a second sample")

// parseGPUEngineInstance splits a PDH "GPU Engine" instance name —
// "pid_1234_luid_0x00000000_0x00011A2B_phys_0_eng_0_engtype_3D" — into PID
// and engine type ("3D", "Copy", "VideoDecode", ...). engType is empty when
// the name carries no engtype marker.
func parseGPUEngineInstance(name string) (pid int, engType string, ok bool) {
	rest, found := strings.CutPrefix(name, "pid_")
	if !found {
		return 0, "", false
	}
	digits, rest, found := strings.Cut(rest, "_")
	if !found {
		return 0, "", false
	}
	pid, err := strconv.Atoi(digits)
	if err != nil || pid < 0 {
		return 0, "", false
	}
	const marker = "engtype_"
	if i := strings.LastIndex(rest, marker); i >= 0 {
		engType = rest[i+len(marker):]
	}
	return pid, engType, true
}